1. Field of the Invention
The present invention relates generally to a flat panel display device. More particularly, the present invention relates to an organic light emitting display device employing a simultaneous emission driving technique, and a method of driving the organic light emitting display device.
2. Description of the Related Art
Recently, an organic light emitting display device is widely used as a flat panel display device included in an electronic device. A technique for driving the organic light emitting display device may be classified roughly into a sequential emission driving technique and a simultaneous emission driving technique. Specifically, the sequential emission driving technique sequentially performs a scanning operation by each scan-line, and then sequentially controls pixel circuits to emit light by each scan-line (i.e., sequentially performs a light emitting operation). On the other hand, the simultaneous emission driving technique sequentially performs the scanning operation by each scan-line, and then controls all pixel circuits to simultaneously emit light (i.e., simultaneously performs a light emitting operation).
Generally, in the simultaneous emission driving technique, a frame operation period for displaying one image frame may include an initialization period for performing an initializing operation, a reset period for performing a resetting operation, a threshold voltage compensation period for performing a threshold voltage compensating operation, a scan period for performing a scanning operation, and an emission period for performing a light emitting operation. Here, each of the initializing operation, the resetting operation, the threshold voltage compensating operation, and the light emitting operation is simultaneously performed for all pixel circuits, whereas the scanning operation is sequentially performed for all pixel circuits by each scan-line.
As described above, when the simultaneous emission driving technique implements (i.e., displays) one image frame, the scanning operation is sequentially performed for all pixel circuits by each scan-line. Thus, a delay (e.g., about 3 ms˜4 ms) may occur between the time when a data signal is applied to pixel circuits coupled to upper scan-lines (or lower scan-lines) and the time when a data signal is applied to pixel circuits coupled to the lower scan-lines (or the upper scan-lines) because the scanning operation is sequentially performed from a top scan-line to a bottom scan-line, or from the bottom scan-line to the top scan-line.
However, the light emitting operation is simultaneously performed for all pixel circuits to implements one image frame. Thus, an emission waiting time (i.e., a waiting time for the light emitting operation) of the pixel circuits coupled to the upper scan-lines (or the lower scan-lines) may be longer than an emission waiting time of the pixel circuits coupled to the lower scan-lines (or the upper scan-lines) if the scanning operation is sequentially performed from the top scan-line (or the bottom scan-line) to the bottom scan-line (or the top scan-line). Thus, a difference between these emission waiting times may result in a voltage drop due to a leakage current, etc (i.e., a change of a data voltage stored in a storage capacitor of respective pixel circuits). As a result, the luminance uniformity of a display panel included in the organic light emitting display device may be greatly degraded.